Device and method for application of a gluing system

ABSTRACT

A device for application of a gluing system of at least two components, such as a resin component and a hardener component comprising a unit of at least two hollow members, at least one member for each component, provided with a number of orifices in each member designed to apply the respective component onto a substrate below the hollow members to form strands, the hollow members being positioned above the plane of application, wherein the unit comprises means for adjusting the position of the orifices in at least one of the hollow members in relation to the position of the orifices in the other hollow members. The invention also relates to a method for applying a gluing system of at least two components, such as a resin component and a hardener component, in the form of strands, using the device.

This application is a 371 of PCT/GB99/01083 filed Jan. 16, 1999, whichclaims benefit of provisional applications 60/091,038 filed Jul. 1,1998, and 60/091,498 filed Jul. 1, 1998, and 60/091,442 filed Jul. 7,1998.

The present invention relates to a device for separate application of agluing system comprising at least two components, such as a resincomponent and a hardener component, onto a substrate, and an applicationmethod wherein said device is used.

Separate application of the components of a gluing system, such as resinand hardener components, is known in the art of gluing and offers theadvantages of providing the components applied onto the substrate in anot thoroughly mixed condition. The actual mixing of the componentsapplied is obtained in the further processing of the substrate, such asthe pressing of two or more such substrates together, allowing for alonger period of time to lapse between application and pressing, withoutan undesired extent of curing occurring during said period. Also, sincethe components are separated in the application device the pot life ofthe gluing system will be markedly extended, and the risk of cloggingwill be brought to a minimum.

Sequential application in the form of strands of resin and hardenercomponents by means of an application device comprising twoindependently mounted tubes, cf. SE-373 525, having a row of orificesthrough which the resin and hardener components are separately spreadafter each other onto the substrate, has been used in the prior art inthe case of application of phenolic resorcinol gluing systems. This typeof application results in more or less random distribution of thestrands of one component in relation to the strands of the othercomponent onto the substrate.

Another method of applying resin and hardener components is a specialtype of curtain application, for example, as that described in EP 286939 B1. However, in this method a large surface area of the componentsare exposed to the surrounding atmosphere, leading to increasedevaporation of the water contained in the components of the gluingsystem. Accordingly, this incurs a reduced period of time from theapplication of the components to application of pressure for pressing,which is a disadvantage when gluing large wooden beams, for instance.

Further, in the case of curtain application, it is hard to prevent theapplied components from dripping off from the lamella when the lamellais turned 90 degrees (after the application, which is often necessarysince the pressing equipment is often constructed such that the pressureis applied horizontally, i.e., the glue joints will be vertical. Thus,this method of application is more sensitive to variations in viscositythan the strand application method.

However, technical solutions are still sought for the need to findapplication systems for separate application of the components of agluing system, which can be adjusted to the gluing system in questionand the desired assembly times. By assembly time it is meant the timethat lapse from the moment of application of a gluing system onto asubstrate to the moment of pressing the substrates to be glued together.

The present invention accordingly provides a device, and a method usingthe device, by which the above-mentioned problems are overcome.

The device according to the invention is defined in the appended claims.It comprises a unit of at least two hollow members, at least one memberfor each component, provided with a number of orifices, from whichorifices in each member designed to apply the respective component ontoa substrate below the hollow members to form strands, the hollow membersbeing positioned above the plane of application, wherein the unitcomprises means for adjusting the position of the orifices in at leastone of the hollow members in relation to the position of the orifices inthe other hollow member(s).

The means for adjusting the position of the orifices, in at least one ofthe hollow members, in relation to the position of the orifices in theother hollow member(s), can be a common exchangeable nozzle platecovering at least two hollow members or alternatively it can comprisemeans for moving the hollow members in relation to each other in thecross machine section.

The orifices in the common nozzle plate can be arranged so that thelater applied strands of one component substantially overlap, do notoverlap, or do not contact, respectively, the corresponding strands ofthe previously applied component(s).

A common nozzle plate it may be suitable when the centre to centredistances between the hollow members is from about 5 mm to 900 mm,provided that the total distance, centre to centre, between the two mostdistant hollow members is no more than about 900 mm.

The moving means can move the hollow members in relation to each otherin the cross machine direction. In this way the position of the orificesin at least one of the hollow members can be adjusted in relation to theposition of the orifices in the other hollow member(s). Thus, theposition of the hollow members in relation to each other can be adjustedso that the later applied strands of one component substantiallyoverlap, do not overlap, or do not contact, respectively, thecorresponding strands of the previously applied component(s).

With the device according to the present invention the strands can beapplied safely and carefully at the accurate position on the substrate.

The device can be provided with guiding means, which are connected tothe application unit, in order to prevent the components from fallingonto the edges of the substrate that are not to be glued. The guidingmeans, during application, engage with the contour of the substrate inthe machine direction, while the unit is being held movable in the crossmachine direction.

The method according to the invention is defined in the appended claims.It comprises use of the above-described device for applying a gluingsystem of at least two components, such as a resin component and ahardener component, in the form of strands, onto a substrate.

The substrate is suitable fed under the hollow members through thedevice.

Depending on the reactivity of the components in the gluing system andthe desired assembly times, the later applied strands may overlap, donot overlap, or do not contact, respectively, the correspondingpreviously applied strands of the other components.

As used here, the term “strand” also comprehends the meaning of the term“ribbon”, also conventionally used in the art, and any other like term

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to theaccompanying drawings.

FIG. 1 shows an embodiment of the device according to the invention tobe used with two components, comprising two hollow members, 1 and 2,with a short c/c distance.

FIG. 2, shows an embodiment of the device according to the invention tobe used with two or three different components, comprising three hollowmembers, 1, 2 and 3 and

FIG. 3 illustrates an embodiment having four hollow members, 1, 2, 3 and4.

FIG. 4 shows another embodiment according to the invention with fourmovable hollow members 1, 2, 3 and 4.

FIGS. 5 and 6 show two different positions of the orifices of one hollowmember in relation to the orifices of the other hollow member in thecommon nozzle plate for an embodiment according to FIG. 1. Finally,

FIGS. 7 and 8 show two different positions of one hollow member and itsorifices in relation to the other hollow member and its orifices for anembodiment according to FIG. 4 but with only two hollow members.

DETAILED DESCRIPTION OF THE INVENTION

In the Figures, the strands are designated by the reference numeral 10,and the letters a, b, c, and d, respectively, are used to denote detailspertaining to the hollow member 1, 2, 3, and 4, respectively.

Each hollow member is provided with an inlet 9, through which therespective component is supplied. The device comprises at least twohollow members having a multitude of small holes 6, the members beingfixed to each other in parallel by means of fixation means, forming aunit. The longitudinal axes of the hollow members are placedsubstantially perpendicularly to the machine direction of the devicewith spacing between said members in said direction. The sidewaysdistance(s) between said members can be adjusted.

The small holes 6 of the hollow members are facing the substrate 8. Saidholes constitute orifices for resin and hardener component,respectively, through which the components flow during application. Atleast one hollow member for each of the two above-mentioned componentsis provided in the device. Additional hollow members for application ofthe same or other additional desired components can also be provided inthe device.

The orifices of each member can be at a distance of 2-16 mm, suitably2-5 mm from each other, depending on the specific substrate to whichglue is to be applied. The diameter of said holes can range from 1-10mm, suitably 2-5 mm. A suitable substrate can, for instance, be a woodenlamella. Other substrates that can be used can be made of, for example,metal, plastic, or composite material. If desired, by selection of theproper distances and flow rates, the strands of any given component canbe made to coalesce to an essentially coherent mass.

Suitable amounts of the components to be applied are in the range of200-500 g/m2, depending, interalia, on the feeding rate. At feedingrates below 30 m/min difficulties in dosage are likely to be encountereddue to discontinuous strands emanating from the orifices (dripping). Asuitable feeding speed of the substrates is up to 300 m/min, moresuitably 30-250 m/min, and preferably 60-200 m/min.

In FIG. 1, a device comprising 2 hollow members, 1 and 2, one for resinand the other for hardener components, is shown. The flow rates of thetwo components are adjusted by means of two pumps (not shown).

The holes 6 of the respective hollow members, from which the respectivecomponents are applied to the substrate, can be formed directly in thehollow member and/or in a nozzle plate as represented by referencenumeral 5. Depending on the distance between the hollow members, two ormore of the members can have a common nozzle plate 5, as shown in FIGS.1, 2, and 3. A common nozzle plate is suitable when the centre to centredistances between the members are relatively short, e.g. 5-40 mm.

Depending on which arrangement of the position of the orifices of thehollow members in relation to each other within the common nozzle plate5 that is desired in each occasion, the common nozzle plate 5 can simplybe replaced with another nozzle plate 5 having orifices at suitablepositions.

In FIG. 2, an embodiment such as depicted in FIG. 1 is shown, with theexception of that in the present embodiment three hollow members, 1, 2and 3, are being used, one of which members can be used for the resincomponent, a second for the hardener component, and a third for hardeneradditives, such as for example an accelerator, respectively. Thisembodiment could also be used for application of only two components,such as resin-hardener-resin, for example, or resin and hardenertogether with a third component other than the accelerator.

FIG. 3 shows another embodiment wherein four hollow members, 1, 2, 3 and4, is used for the application of, in the following order; glue,hardener, a hardener additive, such as an accelerator, and finally, glueagain.

FIG. 4 shows another embodiment; wherein the distance centre to centrebetween the hollow members is greater than in FIG. 3. In this embodimentseparate nozzle plates, 5 a-d, are used. Here, instead of fixation means7 as shown in FIG. 1-3, fixation means 12 are used, which allow forregulation of the individual sideways distance between, said members. Inthis embodiment means for moving 11 the hollow members in relation toeach other in the cross machine direction are used.

In FIG. 5 the orifices of one hollow member in relation to the orificesof the other hollow member, within a common nozzle plate 5 are shown,wherein each of the orifices 6 a in one of the hollow members arealigned in the machine direction with the corresponding orifices 6 b ofthe other hollow member. FIG. 7 also shows the orifices of two hollowmembers being aligned in relation to each other in the cross machinedirection, with the exception that the hollow members here do not have acommon nozzle plate and the position of the hollow members is adjustedby the moving means 11 in the cross machine direction. The embodimentsshown in these figures enable application of a resin and a hardener ontoa substrate, wherein the later applied strands of one component areoverlapping the previously applied strands of the other component.

FIG. 6 shows an embodiment with two hollow members with a common nozzleplate 5, wherein each of the orifices 6 a in one hollow member areparallel displaced in the machine direction in relation to thecorresponding orifices 6 b of the other hollow member. FIG. 8 shows anembodiment with two hollow members without a common nozzle plate,wherein one hollow member is moved in the cross machine direction, inrelation to the other hollow member so that each of the orifices 6 a ofone hollow member are parallel displaced in the machine direction, inrelation to the corresponding orifices 6 b of the other hollow member.The embodiments shown in these figures enable application of a resin anda hardener onto a substrate, wherein the later applied strands of onecomponent are applied at a certain distance 13, depending on the gluingsystem used and the wanted assembly time, in relation to the previouslyapplied strands of the other component.

Depending on the reactivity of the components of the gluing system andthe desired assembly time, the strands of the different components, suchas the hardener and the resin, can be applied in relation to each otherin various suitable ways. Thus, for low reactive/slow curing gluingsystems, and/or short assembly times, it is suitable that the laterapplied strands of one component overlap the corresponding strands ofthe previously applied component(s), or they are applied adjacent toeach other so that they are in essentially contact with each other. Whenhigh reactive/fast curing gluing systems are used, and/or long assemblytimes are desired, it is suitable that the later applied strands of onecomponent are applied with a certain distance 13 in relation to thecorresponding strands of the previously applied component(s). Forassembly times of about 60-120 min a distance of about 4-8 mm betweenthe strands of the different components of the gluing system, such asthe hardener and the resin, is suitable, for assembly times of about15-60 min a distance of about 24 mm is preferred, and for assembly timesof about up to 15 min overlapping of the strands or essentially contactbetween them is preferred.

According to one embodiment of the present invention the strands ofresin and hardener components, respectively, are applied uniformly aftereach other so that essentially continuous contact of each strand of onecomponent with each corresponding strand of the other component(s) isachieved throughout the length of the strands. That is, the laterapplied strands of one component will normally substantially overlap thecorresponding strands of the previously applied component(s). Thereby, arelatively smaller strand, normally the hardener component, can bebrought to lie substantially within the width of a larger strand, e.g.,on top of, or under a larger strand, depending on the order ofapplication. The strands of one component can also be applied in suchclose proximity to the adjacent similar strands so that, when applied tothe substrate, said strands form an essentially coherent liquid mass, onto which mass, subsequently, an essentially coherent mass of a secondcomponent can be formed in the same manner.

According to one embodiment of the invention, there is provided adevice, by means of which the components can be prevented from fallingonto the edges of the substrate that are not to be glued, and therebyeliminate any faulting or other negative effects resulting from thecomponents contacting undesired areas of the substrate. Thereby, alsothe glue waste is reduced. In this embodiment the device is providedwith guiding means (not shown), as conventionally used in the art. Saidguiding means, which is held in contact with the contour of thesubstrate, i.e., the side edges of the substrate in the direction ofmotion, is connected to the unit, which in turn is mounted movably inthe cross-direction of the device, whereby a contour-following movementof the unit comprising the hollow members during the application of thecomponents is established. The substrates used together with thisembodiment can be somewhat curved or twisted while the above-describedadvantages still are obtained

By the use of guiding means in the application according to theinvention, one avoids the spreading of any of the components on theouter surfaces of and the amount of waste, or the need for thecollecting and/or recirculation of any excessive volumes of thecomponents used falling outside the substrate is thereby reduced to aminimum. The guiding means can for example be comprised of guidingplates, which are mounted on a common axis with the distance betweensaid guiding plates being adjustable in order to match different widthof substrates used.

The holes 6 of the hollow members 1,2,3,4 can be covered from inside bymeans of a rod-shaped device (not shown), operated from outside, thatcan be brought into said member from the end thereof, parallel to thelongitudinal axis thereof, and locked in the desired position in orderto adjust the number of the open holes 6 to the width of the specificsubstrate 8. The way of regulating the width used of the hollow membersto the width of the substrate is not critical and can be accomplished inany suitable manner.

The device according to the invention can have a start stop and/or acirculating system.

The distance between the centres of the hollow members 1,2,3,4 isdependent on the method of feeding the components to the members, a fewexamples of which will be described hereinafter, and the number ofmembers used, and can range from about 5 to 900 mm.

Thus, as an example, in the case of an embodiment of the inventionhaving four hollow members, as shown in FIGS. 3 and 4, a suitabledistance from the centre of the one outer hollow member to the centre ofthe other outer member (i.e., 1 and 4 in the figures) is in the range ofabout from 15 to 900 mm. With only two members, as shown in FIG. 1, thedistance from centre to centre is from about 5 to 900 mm, a suitablerange being 40 to 300 mm. In any case, for practical considerations, thetotal distance should suitably not exceed about 900 mm.

In the case of separate continuous recirculation of the respectivecomponents, the excessive amounts of the components not applied to thesubstrate 8, collected in the respective collecting trays (not shown)positioned under the hollow members, are directed back to the respectivehollow member by means of pumping, together with the components fed fromthe supply tanks. Thus, the components are continuously running from therespective members. Here, a larger distance, such as about 300 to 900mm, is preferred in order to prevent any splatter of the first componentfrom the front of a lamella to reach in to the collecting tray of theother component as mentioned above.

In the case of the so called start/stop operation, there are twodifferent types of pumping in order to feed the components to the hollowmembers, firstly, a simple type, and secondly, a more elaborate one. Inthe first type the pumping of the respective component is switched onshortly before the front of the lamella reaches the respective hollowmember, and then shortly after the passage, is switched off again. Thesecond type is based on continuous circulation by means of pumping ofthe components in different circulation lines, from which lines therespective components are drained to the hollow members by means of3-way valves. This latter method makes the start and stop of theapplication of the components more instant, due to the continuouspressure maintained in the circulating lines. The amount of thecomponents not falling onto the substrate in the start/stop operationmode will in either case constitute the glue waste. In the former typesaid waste will typically be of the order 2-4%, and in the latter evenless.

In case of the start/stop operation, the distance between the centres ofadjacent hollow members can be reduced to 5 mm, whereby the equipmentcan be made relatively small and easy to adjust to already existingmanufacturing lines. The short distance will also improve the accuracyof the application according to the present invention.

From a working place environmental consideration, the start/stopoperation is normally preferred, since any undesired emissions from thegluing system components in the respective collecting trays are reduced.Also, by not having the components continuously running from the hollowmembers, any such emissions are reduced.

The order of application of the resin and hardener components,respectively, is not critical and can be chosen as appropriate dependingon the substrate, the specific components used, the subsequentprocessing, and the desired characteristics of the ultimate product. Byusing the device according to the invention hardeners comprisingaggressive acids could be used since they can be prevented from gettinginto direct contact with the substrate. For example, this can beachieved by the application of the sequence of resin-hardener-resin,thereby securing the contact of the substrate with only the resincomponent, even when gluing said substrate together with another pieceof substrate not provided with glue.

Also, when using a component comprising a substance which desirablyshould be prevented from being emitted into the atmosphere, or into aspecific surrounding environment for any reason, such as for example avolatile acid in the hardener component, such component can suitably beapplied followed by at least one other component covering the componentcomprising the substance to be prevented from being emitted. Forinstance, in case of application of a gluing system comprising a resincomponent and a hardener component, the latter of which comprises avolatile acid, such as formic acid, acetic acid or pyrovic acid, whichacid not necessarily must be prevented from contacting the substrate, asuitable order of application would be the hardener component first,which thereafter is covered with the resin component.

Thus, the device and method according to the present invention offermany advantages, such as, for example, reduced glue waste, improvedworking environment during application, the possibility of gluingsubstrates which are sensitive to one of the components used, and alsothe benefits of a volume-effective system.

Examples of gluing systems which can be used together with the deviceaccording to the present invention are urea-formaldehyde,melamine-urea-formaldehyde, phenol-resorcinol-formaldehyde, emulsionpolymer isocyanate, two component polyvinyl acetate, and two componentpolyurethane gluing systems.

The device according to the present invention can, for example,advantageously be used in a method of separate application of resin andhardener components of an amino resin gluing system wherein bothcomponent are applied in the form of strands in optional order ofapplication, wherein the first applied component optionally can coalesceto form an essentially continuous layer thereof, onto which the othercomponent is applied.

Another method wherein the present device suitably can be used is amethod comprising separate application of resin and hardener componentsof an expandable gluing system in the form of strands, wherein saidhardener component is acidic, and the resin component comprises one ormore gas generating substances capable of forming a gas when contactedwith said hardener component. The gas generating substance can be anycarbonate or hydrogen carbonate that will generate CO₂ upon contact withan acid. Suitable examples are, for instance, sodium hydrogen carbonate,calcium carbonate, sodium carbonate, ammonium carbonate, ammoniumhydrogen carbonate, magnesium carbonate, or a mixture thereof.

While the present invention has been described with reference toembodiments wherein the substrate is being fed in the machine directionunder the unit comprising the hollow members, the converse mode ofoperation is also conceivable within the scope of the appended claims,i.e., the substrate could be immobile with the unit passing above itduring application of the components.

What is claimed is:
 1. A device for application of a gluing system of atleast two components, comprising a unit of at least two hollow members,at least one member for each component, provided with a plurality oforifices in each member designed to apply the respective component ontoa substrate below the hollow members to form strands, the hollow membersbeing positioned above the plane of application, wherein the unitcomprises means for adjusting the position of the orifices in at leastone of the hollow members in relation to the position of the orifices inthe other hollow member(s), wherein the means for adjusting the positionof the orifices is a common exchangeable nozzle plate covering at leasttwo hollow members.
 2. The device according to claim 1, wherein theorifices for each of the hollow members in the common nozzle plate canbe arranged so that the later applied strands of one componentsubstantially overlap the corresponding strands of the previouslyapplied component(s).
 3. The device according to claim 1, wherein theorifices for each of the hollow members in the common nozzle plate canbe arranged so that the later applied strands of one component do notoverlap the corresponding strands of the previously appliedcomponent(s).
 4. The device according to claim 1, wherein the orificesfor each of the hollow members in the common nozzle plate can bearranged so that the later applied strands of one component do notcontact the corresponding previously applied strands of the othercomponent(s).
 5. The device according to claim 1, wherein the distancecenter to center between the hollow members is from about 5 mm to about900 mm, provided that the total distance, center to center, between thetwo most distant hollow members is no more than about 900 mm.
 6. Thedevice according to claim 1, wherein the unit is provided with guidingmeans connected to the unit, which means during application engage withthe edge contour of the substrate in the machine direction, the unitbeing movable in the cross machine direction.
 7. The device according toclaim 1, wherein the at least two components comprises at least oneresin component and at least one hardener component.
 8. A device forapplication of a gluing system of at least two components, comprising aunit of at least two hollow members, at least one member for eachcomponent, provided with a plurality of orifices in each member designedto apply the respective component onto a substrate below the hollowmembers to form strands, the hollow members being positioned above theplane of application, wherein the unit comprises means for adjusting theposition of the orifices in at least one of the hollow members inrelation to the position of the orifices in the other hollow member(s),wherein the means for adjusting the position of the orifices comprisesmeans for moving the hollow members in relation to each other in thecross machine direction.
 9. The device according to claim 8, wherein theposition of the hollow members in relation to each other can be adjustedso that the later applied strands of one component substantially overlapthe corresponding strands of the previously applied component(s). 10.The device according to claim 8, wherein the position of the hollowmembers in relation to each other can be adjusted so that the laterapplied strands of one component do not overlap the correspondingstrands of the previously applied component(s).
 11. The device accordingto claim 8, wherein the position of the hollow members in relation toeach other can be adjusted so that the later applied strands of onecomponent do not contact the corresponding previously applied strands ofthe other component(s).
 12. The device according to claim 1, wherein theat least two components comprises at least one resin component and atleast one hardener component.
 13. A method for applying a gluing systemof at least two components on a substrate, by using a device comprisinga unit of at least two hollow members, at least one member for eachcomponent, provided with a plurality of orifices in each member designedto apply the respective component onto a substrate below the hollowmembers to form strands, the hollow members being positioned above theplane of application, the unit comprising means for adjusting theposition of the orifices in at least one of the hollow members inrelation to the position of the orifices in the other hollow member(s),said means for adjusting the position of the orifices being a commonexchangeable nozzle plate covering at least two hollow members, whereinat least two components are separately applied from separate hollowmembers after each other, in the form of first applied strands, andlater applied strands, onto the substrate.
 14. The method according toclaim 12, wherein the substrate is fed under the hollow members throughthe device.
 15. The method according to claim 13, wherein the laterapplied strands of one component substantially overlap the correspondingpreviously applied strands of the other component(s).
 16. The methodaccording to claim 13, wherein the later applied strands of onecomponent do not overlap the corresponding previously applied strands ofthe other component(s).
 17. The method according to claim 13, whereinthe later applied strands of one component do not contact thecorresponding previously applied strands of the other component(s). 18.A method for applying a gluing system of at least two components onto asubstrate, by using a device comprising a unit of at least two hollowmembers, at least one member for each component, provided with aplurality of orifices in each member designed to apply the respectivecomponent onto a substrate below the hollow members to form strands, thehollow members being positioned above the plane of application, the unitcomprising means for adjusting the position of the orifices in at leastone of the hollow members in relation to the position of the orifices inthe other hollow member(s), said means for adjusting the position of theorifices comprises means for moving the hollow members in relation toeach other in the cross machine direction, wherein at least twocomponents are separately applied from separate hollow members aftereach other, in the form of first applied strands, and later appliedstrands, onto the substrate.
 19. The method according to claim 18,wherein the substrate is fed under the hollow members through thedevice.
 20. The method according to claim 18, wherein the later appliedstrands of one component substantially overlap the correspondingpreviously applied strands of the other component(s).
 21. The methodaccording to claim 18, wherein the later applied strands of onecomponent do not overlap the corresponding previously applied strands ofthe other component(s).
 22. The method according to claim 18, whereinthe later applied strands of one component do not contact thecorresponding previously applied strands of she other component(s).